I would like to boot from my x86 system that I compiled on /dev/sda4 partion (built on my nomultilib profile while chrooted; Root is at /home/gentoo32 ). The 32 bit kernel and initramfs were then copied to my boot partition (/dev/sda1). I did not install grub (grub-install) while chrooted in the 32bit environment. Its fstab looks like this:

When the kernel mounts root, the root of the filesystem becomes /. You could work around this with an initramfs that chroots into the effective root, but I do not understand why you even want to boot a 32-bit kernel. You have already demonstrated that your 64-bit kernel can run 32-bit code. Running the 32-bit environment in its chroot should be sufficient for any legacy x86 programs you need to run.